Wa-Wm

 

wadi

A dry stream bed. This term, of Arabic origin, has also been spelled as ``ouadi''.

 

Walker circulation

A name coined by Bjerknes for two circulation cells in the equatorial atmosphere, one over the Pacific and one over the Indian Ocean. Schematically these are longitudinal cells where, on one side of the ocean, convection and the associated release of latent heat in the air above lifts isobaric surfaces upward in the upper troposphere and creates a high pressure region there. The lack or lesser degree of the same process on the other side of the ocean results in lower pressure there, and a longitudinal pressure gradient is established which, being on the equator, cannot be balanced by the Coriolis force. Thus a direct zonal circulation is driven in the equatorial plane with countervailing winds at the surface and in the upper troposphere, with concomitant rising and sinking branches on the appropriate sides of the ocean.

The normal Walker circulation in the Pacific consists of air rising over Indonesia, west winds in the upper troposphere, sinking air off the west coast of South America, and east winds near the surface. A reversed but weaker Walker circulation (and an enhanced Hadley circulation occurs during ENSO years. In the Indian ocean the circulation cell proceeds in the opposite sense (to the normal Pacific Walker cell), with sinking air over cold waters off the Somali coast and a low-level acceleration from west to east along the equator in the lower atmosphere. See Henderson-Sellers and Robinson (1986) and Kraus and Businger (1994).

 

WAMDI

Acronym for Wave Model Development and Implementation group, an organization created to advanced sea surface state models. See Group (1988).

 

WAMEX

Acronym for the West African Monsoon Experiment, a component of FGGE designed to study monsoonal circulations.

 

Warm Deep Water

See Antarctic Circumpolar Water.

 

Warthe-Weischel

The American name for the glacial period that started 110,000 years ago and lasted 100,000 years. It featured extensive ice cover in North America and Northern and Central Europe, most of which disappeared during a warm interstadial. There were also three stadials during this period, which is called the Wurm period in the Alpine system and the Wisconsin period in the Scandinavian system. The was preceded by the Saale period.

 

water mass

In physical oceanography, a body of water with a common formation history. A water mass is identified through relationships on a T-S diagram, although additional information about the degree of spatial and temporal variability during its formation as expressed by a standard deviation is almost always needed as well. A single T-S point, i.e. a water type, along with its standard deviation, may be sufficient for identification (especially with deep water masses), although generally a set of T-S combinations, i.e. a function in T-S space, is needed along with a standard deviation envelope. Generally the standard deviation decreases with depth. In practice not enough data is usually available to calculate a standard deviation, so a point or line in T-S space is specified around which the water mass properties are presumed to vary.

Examples include AAIW, AASW, SAMW, SAUW, AACW, WDW, AABW, ABW, GSDW, ASW, PDW, SIW, WSPCW, ESPCW, WNPCW, ENPCW, NPEW, SPEW, JSMW, JSPW, IDW, PGW, ICW, AAMW, BBW, LSW, EMW, AIW, SACW, NACW, MMW, MDW, AW, and LIW.

 

water type

In physical oceanography, a point on a T-S diagram.

 

water vapor feedback

A positive feedback loop in the atmosphere wherein an increase in temperature increases the water holding capacity. This will lead to an increase in the amount of atmospheric water vapor which, being a greenhouse gas, will in turn lead to another temperature increase. This process is better understood in the lower troposphere where there is reasonable certainty as to the feedback process. The upper atmosphere, while not as well understood in this regard, has a preponderance of evidence pointing to this. The temperature change is not uniform with height and the resulting changes in the vertical temperature gradient can partially compensate for the water vapor feedback.

 

water vapor mixing ratio

The ratio of the mass of water vapor to the mass of dry air in a specified volume as expressed in grams per kilogram.

 

water vapor pressure

The part of atmospheric pressure due to the water vapor in the atmosphere.

 

WATTS

Acronym for Western Atlantic Thermohaline Transport Study.

 

waveband

A band or range of continously contiguous frequencies in a given larger range.

 

WBC

Abbreviation for Western Boundary Current.

 

WBGU

Abbreviation for Wissenschaftlicher Beirat Globale Umweltveranderungen or, in translation, the German Advisory Council on Global Change. The objectives of this council are to evaluate scientific knowledge concerning all aspects of global environmental change in the interdisciplinary context of the Earth system, and to formulate recommendations for political action on the basis of this knowledge. See the WBGU Web site.

 

WCASP

Abbreviation for the World Climate Applications and Services Program, a major component of the WMO-coordinated WCP.

 

WCDMP

Abbreviation for the World Climate Data and Monitoring Program, a major component of the WMO-coordinated WCP. The purpose of WCDMP is to ensure that WMO members have access to reliable climate data and producted derived from existing observations of the climate climate system in formats suitable for their use. More information can be found at the WCDMP Web site.

 

WCIRP

Abbreviation for the World Climate Impact Assessment and Response Strategies Program, a major component of the WMO-coordinated WCP. This program is the responsibility of UNEP.

 

WCMC

Abbreviation for World Conservation Monitoring Centre, which provides information services on the conservation and sustainable use of species and ecosystems. See the WCMC Web site.

 

WCP

See World Climate Program.

 

WCRP

Abbreviation for World Climate Research Program, a major component of the WMO-coordinated WCP. The WCRP is jointly implemented by the WMO, the ICSU, and the IOC. The purpose of the WCRP is to develop the fundamental scientific understanding of the climate system and climate processes that is needed to determine to which extent climate can be predicted and the extent of man's influence on climate. See the WCRP Web site.

 

WDC

Abbreviation for World Data Centre, an ICSU project.

 

WDW

See Warm Deep Water.

 

Weak Sun Paradox

See Faint Young Sun Paradox.

 

weather

That which everybody talks about but nobody does anything about. The weather, as distinguished from the climate, consists of the large fluctuations in the atmosphere from hour-to-hour or day-to-day. These occur as weather systems move, develop, evolve, mature and decay as forms of atmospheric turbulence. Weather systems originate mainly from atmospheric instabilities and their evolution is nonlinear, making them unpredictable beyond a week or two into the future. They most likely never will be predictable beyond that due to the inherent properties of systems governed by chaotic dynamics. See Houghton and Filho (1995).

 

Weddell Gyre Boundary

See Continental Water Boundary.

 

Weddell Sea Bottom Water

A type of water found in the seas surrounding Antarctica with temperatures ranging from -1.4 to 0.8 deg. C and salinities of 34.65 ppt. It underlies Antarctic Bottom Water (AABW) and is found on the slopes and southern and western ages of the Weddell Sea basin.

 

Weddell Deep Water

In physical oceanography, a water mass type formed in the Weddell Sea by surface cooling and subsequent convection in the polyna. This water has stable properties with a potential temperature between 0.4-0.7 deg. C. WDW mixes with water above the continental slope in the Weddell Sea to serve as one source for Antarctic Bottom Water. See Tomczak and Godfrey (1994), p. 84.

 

well mixed estuary

One of four principal types of estuaries as distinguished by prevailing flow conditions. In this type the water column is (as you might have guessed) well mixed with essentially no variation in salinity in a vertical column. The Thames estuary is an example of this type.

 

WEPOCS

Acronym for Western Equatorial Pacific Ocean Circulation Study.

 

western boundary current

The intensification of the western limb of an oceanic circulation gyre. This is inevitable given a rotating earth, a meridional boundary, and a zonal wind stress pattern that reverses direction at some latitude as was shown using a simple dynamical model in the classic paper of Stommel (1948). Common features of such currents include their flowing as swift narrow streams along the western continental rise of ocean basins, their extension to great depth well below the thermocline, and their separation from the coast at some point and continuation into the open ocean as narrow jets that develop instabilities along their paths. The most well-known western boundary currents are the Gulf Stream and the Kuroshio Current. See Hogg and Johns (1995).

 

Western North Pacific Central Water

In physical oceanography, the dominant water mass in the northern subtropical gyre, formed and subducted in the northern STC. This is fresher than NPEW at all temperatures and saltier than ENPCW except at temperatures above about 17 deg. C (the upper thermocline). It is separated to the east from ENPCW at around 170 deg. W and to the south from NPEW at around 12-15 deg. N. See Tomczak and Godfrey (1994), p. 165.

 

Western South Pacific Central Water

In physical oceanography, a water mass which is one of six distinguishable Central Water masses in the Pacific Ocean. Its T-S properties are almost indistinguishable from those of ICW and SACW, indicative of similar atmospheric conditions during formation. It is formed and subducted in the STC between Tasmania and New Zealand, and is geographically restricted by that and Australia at 150 deg. W. It is separated to the east from the fresher ESPCW in a broad transition zone between 145 and 100 deg. W, and to the north from SPEW, fresher above 8 deg. C and saltier below, at around 15 deg. S. See Tomczak and Godfrey (1994), p. 164.

 

WESTRAX

Acronym for WEStern TRopical Atlantic eXperiment. See Brown et al. (1992).

 

wet-bulb temperature

The temperature obtained by covering the bulb of a dry-bulb thermometer with a silk or cotton wick saturated with distilled water and drawing air over it at a velocity not less than 1000 ft/min. This is often accomplished by swinging the covered thermometer on the end of a string or rope. If the atmosphere is saturated with water vapor, the water in the wick will not evaporate and the dry and wet bulb temperatures will be the same. If the atmosphere is not completely saturated, the water will evaporate from the wick at a rate depedent upon the degree of saturation. The evaporation will cool the bulb and lower the temperature reading over that of the dry-bulb temperature to that of the wet-bulb temperature.

 

WGNE

Abbreviation for Working Group on Numerical Experimentation.

 

white noise

Noise that results in a spectrum where all frequency components have the same amount of energy. This can also refer the the resulting spectrum as well as the process. Compare to red noise.

 

White Sea

One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located to the west of the Barents Sea and is otherwise landlocked.

 

WHOI

Abbreviation for Woods Hole Oceanographic Institution. See the WHOI Web site.

 

WHYCOS

Acronym for the World Hydrological Cycle Observing System, an HWRP project to identify and establish a global network of stations on the major rivers of the world where flow rate, a number of water quality variables, and on-bank climate variables would be measured continuously. See the WHYCOS Web site for more information.

 

Wien displacement law

In radiation transfer, a law stating that the wavelength of maximum emission for a body at a particular temperature is inversely proportional to the temperature and is given by

where T is the temperature (K). The temperature of a black body can be determined from the wavelength of maximum monochromatic radiation using this relation. The maximum emission wavelengths for the Sun and the Earth calculated from this are, respectively, 0.50 m and 11.4 m.

 

williwaw

A violent squall in the Straits of Magellan. This is a region where the winds are almost constantly strong and westerly.

 

wind chill temperature

The hypothetical air temperature in calm conditions that would cause the same heat flux from the skin as occurs for the true winds and the true air temperature.

 

Winter Water

See Subantarctic Mode Water.

 

Wisconsin

The Scandinavian name for the Warthe-Weischel glacial period.

 

Wisconsin school

In phytosociology, a school based on the individualistic concept of the plant association. This school is known for its pioneering use of ordination methods. See Bray and Curtis (1957) and Collinson (1988).

 

WKB approximation

More later.

 

WMO

See World Meteorological Organization.

 

WMOSA

Abbreviation for WMO Satellite Activities, the purpose of which is to coordinate environmental satellite matters and activities throughout all WMO programs and to advise on the potentialities of remote-sensing techniques. See the WMOSA Web site for further information.